1. Technical Field
The present invention relates to a method for producing a visual rhythm; and, more particularly, to a method for producing a visual rhythm which is a single image summarizing changes of video contents by using a pixel sampling technique, and employing the visual rhythm at various digital video application systems and each of digital video related software products.
2. Description of the Related Arts
Presently, according as a digital application field, for example, a broadcasting digital video signal editing, a digital library, a video database, a multimedia video contents production, and a video streaming at an internet, increases, a video indexing research has become active.
As is well known, since a video signal comprises a sequence of image xe2x80x98framesxe2x80x99, all of the video contents are recognized through a control function of a VCR (Video Cartridge Recorder), i.e., a play function, a fast play function, a rewind function and a temporary stop function etc.
The video indexing is a mechanism capable of approaching to a certain portion of the video signal. The video indexing technique has two sorts: annotation-based indexing and content-based indexing. indexing. The annotation-based indexing technique searches a specified section of the video contents through the annotations that are keywords or texts made by an annotator.
On the other hand, the content-based indexing technique searches a specified section of the video contents through the analysis of the video signal characteristics.
Preferably, an effective video indexing technique may be to employ two techniques together, i.e., searching of a specific part of video contents is performed based on both annotations and contents-based indexes.
The most important thing in the content-based indexing technique is a xe2x80x98shot change detectionxe2x80x99.
The video signal is made and edited by a xe2x80x98shotxe2x80x99 unit. The shot is a unit of action photographed without interruption and constituting a single camera view. In general, the duration of one shot is between one or ten seconds according to the contents of the video.
Since the video signal is made by the shot unit, it is necessary to index the video signal based on the shot unit.
In case that the shot change detection is performed manually, the detection cost and the detection time are increased. Therefore, a software has to be employed to automatically detect the shot change detection.
However, it is impossible to perfectly detect all of shots of the video signal with the software. During the automatic detection, there occur false positive shots and missing shots. This is originated from the editing effect.
The editing connects each of the shots by using cut, dissolve and wipe effects. The cut simply connects two adjacent shots. This is called as an abrupt change. On the other hand, the dissolve and the wipe gradually connect two shots through a number of frames. They are called as gradual changes.
A cut is simply a concatenation of two shots. In other words, no special effects are introduced. A dissolve is a simultaneous application of a fade-out (of an outgoing shot) and a fade-in (of an incoming shot). A wipe is another edit effect where an incoming shot appears at one or more parts of an outgoing shot, and then grows gradually until it covers the entire frame.
Recently, according as a digital editing equipment is advanced, three-dimensional editing techniques such as rolling, flying, and Doppler effects are also well known.
A shot boundary detection detects a shot boundary at the edited video signal.
Generally, the shot boundary at the abrupt change such as the cut is easily detected by using a pixel based comparison of signal characteristics, a frame-to-frame comparison of average signal characteristics, a histogram, and a motion. In this case, however, some cases such as shots having camera movements, i.e. panning and zooming, the shot boundary at a very bright or dark background, or a background having very fast moving objects may not be detected.
On the other hand, the shot boundary of the gradual changes such as the dissolves and the wipes is hardly detected.
The shot boundary detection error at a presently developed shot boundary detection algorithm ranges from 10 to 20% in case that the gradual change hardly occurs. Therefore, the confirmation or the verification of the boundary detection is required.
In the prior art, the confirmation or the verification of the shot boundary detection is performed only with the manual VCR functions, so that the exact verification is not possible.
It is, therefore, an object of the invention to provide a method for producing the visual rhythm by using the pixel sampling technique so as to detect and verify the shot boundary.
In accordance with an aspect of the present invention, there is provided a method for producing a visual rhythm in a video system, comprising the steps of: a) sampling a portion of pixels contained at each of frames; and b) producing the visual rhythm summarizing changes of video contents by using the result of the sampling.
In accordance with another aspect of the present invention, there is provided a computer-readable medium for producing a visual rhythm, comprising the steps of: a) sampling a portion of pixels contained at each of frames; and b) producing the visual rhythm summarizing changes of video contents by using the result of the sampling.